Vehicle Based Waveform Laser Scanning in a Coastal Environment

This paper presents the results of an investigation into the use of a waveform lidar system from a ground based vehicle. Data was collected using a Riegl LMS Q560 laser scanner mounted on the roof of a Landrover driven along a 7 km stretch of coastline at Filey Bay, North Yorkshire, UK. An IMU and differential GPS unit, part of IGI’s AeroControl system, were used to provide measurement of sensor orientation and position. Data with an average spatial resolution of 20 cm was collected. The coastline and intertidal zone are notoriously difficult to monitor given the limitations on activity imposed by the tide, extent of coastline, and the limited availability of reliable permanent control. Despite this, the coastal environment is an important asset, the condition of which often needs to be carefully monitored so as to improve the understanding of coastal processes and mechanisms which ultimately leads to improved management decisions and policies. Importantly, not only does the changing topography of coastal cliffs need to be monitored, but so does the profile of the beach and extent and type of vegetation. In many cases, the use of scattered, periodic measurements of coastal change has, therefore, been replaced with airborne survey using photography and/or airborne lidar which provide higher density geometric data. However, despite this, access to data with a high spatial and temporal resolution is still limited. A ground based rapid mapping survey solution may provide a more responsive solution and given the highly dynamic nature of the coastal environment, help to improve the understanding of coastal zone dynamics. Data collection took around 15 minutes, emphasising the appropriateness of the technique to the survey of the coastal zone. This is substantially quicker than the time that would be required to collect comparable data from multiple scans using a conventional static terrestrial laser scanner. The acquired data was quantifiably compared against ground truth data collected within one day of the lidar survey, and also against existing airborne lidar and photogrammetric datasets from previous survey campaigns. The project also considered the potential advantages of using the full laser waveform to improve analysis, in particular in dealing with vegetation along the soft rock cliffs. While the Filey Bay coastline was relatively well suited to the application of such a mobile mapping system, it is recognised that not all coastal sites would be the same. However, there are many other applications where the use of a ground based waveform lidar may be more useful than regular lidar alone, such as in the survey of vegetation along transport routes. This paper, therefore, contributes to the discussion on new methodologies for the rapid survey of linear features, helping to provide managers and engineers with a clearer view of dynamic environments in which it has previously been very difficult to survey using ground based surveying technology.